1. Field of the Invention
The present invention relates to a data partitioning technique-based image compressing method, and more particularly, to a video data coding and decoding apparatus and method for performing an unequal error protection for each partition in image compression.
2. Description of the Background Art
Currently, the next-generation mobile communication system requires a reliable transmission of a high speed multimedia data, for which an intense channel coding and effective modulation method are in demand.
An international mobile telecommunication (IMT)-2000 system which is to be soon realized for a commercial use as the next-generation mobile communication system is a personal globalize multi-service that has standardized various mobile communication systems which had been individually and differently operated by countries so that a user can use the service by using one terminal or a user access card from any place in the world.
In addition, the IMT-2000 system allows a terminal, which ensures a reliable connection quality in various radio signal environment and provides various service of voice/image information and data, to be globally roamed by utilizing the worldwide standardization and the same frequency.
Since the IMT-2000 system can provide high bit rate up to 2 Mbps, it can give us rich multimedia service. And, video application such as video telephony and video surveillance system will be one of killer applications in IMT-2000 services.
FIG. 1 is a schematic view of a conventional H.263 video codec.
As shown in FIG. 1, the conventional H.263 video codec includes an encoder 20 and a decoder 30.
The encoder 20 includes a variable length coder (VLC) 21 which produces variable length bitstream so as to minimize the size of transmitting data.
The decoder 30 includes a variable length decoder (VLD) 31 for source-coding the received coded bit stream so as to restore a video data.
The conventional method in FIG. 1 is so vulnerable to channel error that it may severely reduce the video quality. More specifically, the method does not classify contents of bitstreams according to their importance. So, when less important bits are corrupted, it is very difficult to conceal the error using more important bits (i.e. to recover the image as close to the original image to possible).
In order to solve this problem, the data partitioning method was proposed. FIG. 1 shows the block diagram of the method.
In this method, the variable length coder (VLC) 21 gives the partition mixer 23 partition data. And then, the partition mixer inserts markers and output a coded bit stream.
The partition demixer 33 detects markers and provides partition data to the variable length decoder (VLD) 31.
A video data coding method using the data partitioning technique in the thusly constructed H.263 video codec will now be described.
When a video data is inputted, the VLC 21 of the encoder 20 source-codes the video data and compresses it. And then the VLC 21 partitions the source-coded video data into a plurality of partitions by using a data partitioning technique.
As the partitioning is completed, the encoder 20 inserts a marker into each partition data (a source coding bit), mixes it, and transmits a bit stream with a structure as shown in FIG. 2 to a destination.
The structure of the bit stream, as shown in FIG. 2, includes a slice start code (SSC) 101 indicative of starting of slice, a partition 1 (102), that is, a header containing an information bit, a partition 2 (104) having motion vector (MV) information, a partition 3 (106) having a discrete cosine transform (DCT) coefficient, markers 1 and 2 (103 and 105) for identifying each partition, and a zero bit inserting portion 107 for a byte-aligning.
The VLC 21 marks the boundaries between the partitions 1, 2 and 3 (102, 104 and 106) by inserting the markers 1 and 2 (103 and 105) between the partitioned partitions (102, 104 and 106). The partition 1 is set to have the highest importance, and partitions 2 and 3 are set to have less importance.
Accordingly, even if one partition is damaged due to a channel error, the VLD 31 of the decoder 30 can restore a video data to be as close as possible to the original video data as possible by using the information of the remaining partitions.
That is, if the partition 3 (106) is damaged while being transmitted, the VLD 31 would restore the video data by using the information of the partition 1 (102) and the partition 2 (104). If the partition 2 is damaged, the VLD 31 may restore the video data by using the information of the partition 1 (102).
In this respect, however, if the partition 1 (102) is damaged, the VLD 31 may not restore the original video data with the information of the slice.
As for the mobile data coding method using the conventional partitioning technique, though it is able to prevent error propagation between partitions by partitioning the source-coded video data into a plurality of partitions and inserting the markers between the partitioned partitions, it basically fails to protect the important partition information from an error.
In addition, in the conventional art, if the channel coding is directly adopted to each partition without any consideration, the channel coder might generate the same code with the marker so that the decoder might recognize it as the marker and that makes the decoder work incorrectly.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.